1. Field of the Invention
The present invention relates generally to automotive vehicle sun roofs and more particularly to a sun roof having an improved mechanism for actuating the sliding and tilting operations thereof.
2. Description of the Prior Art
In a known arrangement (see FIGS. 1, 2 and 3 of the drawings), it has been proposed to provide a vehicle 10 with a slidable sun roof 12 comprising a rigid panel 14 slidably mounted on guide rails 16, disposed on the right and left hand sides of a frame 18 attached to the lower surface of the vehicle roof panel 20. With this arrangement, the sun roof may be positioned to close the sun roof opening 22, may be tilted to partially open the opening or may be slidably moved rearwardly into a housing 23 defined between the roof panel 20 and frame 18. The mechanism interconnecting the sun roof and the vehicle by which the sliding and tilting of the sun roof is achieved takes the form of a pair of forward brackets 24 fixed to the lower surface of the sun roof at forward locations thereof. Each bracket is pivotally connected to forward shoes 26 which are respectively slidably received on the guide rails 16. This prior art sun roof is further provided with guide panels 30 in which shaped elongate slots 32 are formed. A pair of rear shoes 34 which slide on the guide rails 16 are fixedly connected to rackwires or cables 28 and are provided with pins 36 which slide in the slots 32 (thus defining a cam and cam follower arrangement). The rackwires or cables 28 extend close to and parallel with the guide rails 16 and are connected to a device (not shown) for moving same in the fore and aft directions of the vehicle. This sun roof arrangement, in order to locate the panel in the appropriate position for closing the sun roof opening 22, is provided with a structural member 38 which serves to limit the forward movement of the forward shoes 26, and another structural member 40 which serves as part of a latch arrangement. A third structural member 42 defines the other part of the latch mechanism and engages the member 40 to prevent the rearward movement of the sun roof.
With this arrangement, when it is desired to open the sun roof, the rackwires 28 are moved in the rearward direction, indicated by the arrow A. The pins 36 are accordingly driven up to the last and highest step of the shaped elongate slot 32, pulling the rear or aft end of the sun roof down into the cavity of the frame 18. Simultaneously, the sun roof pivots about the pivotal connection defined between the forward brackets 24 and the forward shoes 26 causing the forward end of the sun roof to project above the roof panel 20. This particular movement brings the structural members 40 and 42 out of contact, whereby with further rearward movement of the rear shoes (in response to movement of the rackwires 28), the sun roof is then drawn into the housing 23.
To tilt this sun roof for ventilation only, the rackwires are moved in the forward direction, indicated by the arrow B, whereby the rear shoes 34 slide forward. The pins 36 accordingly trace along the slots 32 forcing the rear end of the sun roof to project above the roof panel and the forward end to sink below same (see FIG. 3).
However, this arrangement has suffered from a number of drawbacks. When the sun roof is moved into its storage position, the distance between the forward and rear shoes increases, inviting unstable or jerky sliding. This phenomenon is more pronounced when attempting to move the sun roof back out of the storage position for closing the sun roof opening as the sun roof is virtually pushed from the rear end (in contrast with being pulled from the forward end). This jerky operation, of course, requires a greater force to be applied to the rackwires in order to overcome the braking-like action induced by the jerky sliding. Moreover, the tilting action of the sun roof when ventilation is required rubs a sealing weather strip 44 against the downward depending flange of the roof panel 20 and/or the bathtub-like frame 18. This, of course, hastens the time when the strip will fail to seal the gap between the sun roof and the perimeter of the sun roof opening 22.
For a full and detailed description of the prior art sun roof arrangement set forth hereinabove, refer to U.S. Pat. No. 3,507,537, issued on Apr. 21, 1970, to Herbert Kouth, et al.